1. Field of Invention
The techniques described herein relate generally to enhancement of images and video, and more particularly to preserving and/or enhancing image details when performing luminance contrast enhancement (LCE).
2. Discussion of the Related Art
Digital images may contain pixels that each have associated luminance and chrominance information. Luminance information represents the pixel brightness and chrominance information represents pixel color.
The contrast of an image represents the luminance difference between the dark portions of an image and the light portions of the image. Luminance contrast enhancement (LCE) is a technique for improving image quality by changing the contrast of an image. Changing the contrast of an image by LCE may improve a person's visual perception of the image by accentuating the difference between light and dark portions of an image. Common LCE techniques adjust the luminance levels within the image to fit within the available dynamic range of the application. For example, the contrast may be increased/expanded for a system with high dynamic range, or decreased/compressed for a system with low dynamic range. LCE may use a contrast transfer mapping curve stored in a lookup table to map the current image luminance levels onto new luminance levels. The mapping curve may be linear or non-linear, and may be tailored to a particular application.